Fuse anchor



N A M K R Q J B A lm FUSE Ncnoa Filed June 7. 1939 NVENTQ Y a ORNEY Patented May 4, 1943 FUSE ANCHOR John Alfred Bjiirkman, Johannesburg, Transvaal, South Africa, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain Application June 7, 1939, Serial No. 277,783 In South Africa June 7, 1938 1 Claim.

This invention relates to an improved method of securing a capped fuse to a primer cartridge, and means therefor.

In the art of blasting a detonator is crimped tridge which may be of an explosive or an inerttype and is generally called a primer. -Thereafter the primer is pushed into the drilled hole together with the remaining cartridges of the explosive charge.

In the past, the capped fuse length has been held in position in the hole in the primer against accidental withdrawal during the charging operation, by various means such as tying the string or fixing with metal clips mounted on the primer, or in the case of inert primers by means of glue or wax, or by actually casting or moulding the primer around the capped fuse.

This invention has as an object to devise a new method of securing the capped fuse length in the primer cartridge. A further object is to devise such a method which will be cheap, efficient and easy to operate. A still further object is to provide a new type of clip for holding a. capped fuse length into a primer cartridge. Further objects will appear hereinafter. These objects are accomplished by the following invention.

I have found that I can secure a capped fuse length to the primer by means of a clip which is adapted to be secured to the fuse or to the metal tube of the detonator itself. The free pointed end of the clip is bent inwardly and is so arranged that, on the detonator being inserted in the hole in the primer, the inwardly bent pointed end of the clip is adapted to be pressed into the body of the primer for securing purposes.

The clip, which may be bent from strip metal, wire or the like, is of such length that, when in position on the fuse or detonator, its bent pointed end is positioned beyond the end of the detonator so that all danger of piercing the shell of the detonator is avoided when it is pressed into the it may be bent from wire and secured to the fuse or detonator by being bent to form an eye.

In still a further formthe hole in the attached end of a sheet metal clip is made large enough to pass over the detonator. In this case withdrawal is prevented by bending up a portion of the clip adjacent said hole. An alternative to this method consists in a metal clip having two adjacent holes in the attached end, the metal being bent at a point between the holes to the extent that the holes are concentric. The detonator tube is passed through the holes to the required distance and the metal between the holes is then pressed inwards against the fuse or detonator, locking the clip in position. It is to be understood that the attached end of the clip may surround the fuse or detonator loosely or it may be fixed thereto by being crimped or otherwise deformed so as to grip the fuse or detonator.

In a modified construction the clip may consist of two or more pointed prongs adapted to be pressed into gripping engagement with the primer from different directions. In order that the invention may be more clearly understood and carried into practice reference is now made to the accompanying drawing in which like numerals denote like parts throughout the several views.

In the drawing:

Figures 1 to 7 are pictorial views of various methods of securing the fuse and detonator to the primer by means of metal clips.

Figure 8 is a pictorial view of a preferred shape of a metal clip which is shown in position in Figure 7.

Referring to the drawing, 1 denotes the primer into which is inserted the capped fuse denoted by a 2 which is provided with detonator 3 at its end, the fuse and detonator being secured in the primer by means of a clip 4.

The metal clip 4 illustrated in Figure 1 made from strip metal is secured by its one end to the fuse inwardly of the crimped end of the detonator 3 or to the metal tube of the detonator itself. The securing end 5 of the metal clip 4 is wrapped or looped around the fuse or detonator while the free end 6, which is pointed and bent inwardly is inserted into the body of the primer in a position beyond the end of the detonator.

Figure 2 illustrates a similar method of securing, the clip I being manufactured from wire, the securing end 8 being wrapped or looped around the fuse or metal of the detonator. The pointed free end 9 is similarly inserted-in the primer body in a position beyond the end of the detonator.

Figure 3 illustrates a different means of securing clip 4 to the fuse 3, the clip 4 being provided with a hole in its securing end 5, the hole being of a diameter big enough to allow passage for the fuse but too small for the detonator to pass through, whereby the clip 4 butts against the metal detonator and prevents withdrawal of the fuse when the free pointed end 6 of the clip is inserted in the primer body at a point beyond the detonator end.

The clip illustrated by Figure 4 is constructed similarly to the clip illustrated in Figure 3 and shows the clip applied to the cartridge in a slightly different manner from that of Figure 3.

To secure said clip to the fuse 2, withdrawal is prevented by bending up a portion I of the clip adjacent the said hole.

Figure 5 illustrates clip 4 provided with a collar I I to its end 5 which is adapted to be crimped to the fuse thereby preventing withdrawal.

Figure 6 illustrates a modified construction of the clip which consists of two pointed prongs l2 adapted to be pressed into gripping engagement with the primer from opposite sides. The means of securing said clip to the fuse may be of any of the hereinbefore described methods in a position midway between the prongs.

In the preferred construction of the clip as illustrated by Figure '7 the clip (illustrated separately by Figure 8) is provided at its securing end with two side projections iii, the projections being bent in a U shape. To secure the clip to the fuse or crimped end or the detonator the parallel ends or projections are wrapped or bent tightly around the fuse or detonator. The capped fuse is prevented from withdrawal from the primer when the clip issecured to the primer by having its pointed end 6 inserted therein as previously described. The clip is also provided with a reduced portion or neck l4 facilitating and ensuring bending to the required position.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that the invention is not limited to the specific embodiments thereof except as defined in the appended claim.

I claim:

A clip for securing a capped fuse length to a primer cartridge which comprises a portion of said clip disposed adjacent to the periphery of the cartridge and provided with a bore directed inwardly at an angle to the axis of the cartridge, to hold the capped fuse length in such manner that the cap extends from a locus near the periphery of the cartridge and to a point approximately at the center of said cartridge, a .second portion of the same piece of material as said first portion bent at an angle to said first portion and adapted to lie along the wall of the cartridge and in contact therewith, and a third portion of the same piece of material bent inwardly at an angle to said second portion and adapted to be pressed into the shell wall of the cartridge for securing purposes, all of said portions constituting a single piece of metal.

JOHN ALFRED BJ6RKMAN. 

